charting of cryokarst forms on werenskiold glacier (sw
Transcription
charting of cryokarst forms on werenskiold glacier (sw
Marian PULINA Leszek KOLONDRA Chair of Geomorphology Faculty of Earth Sciences University of Silesia Będzińska 60, 41-200 Sosnowiec POLAND POLISH POLAR STUDIES X X V I Polar Symposium ШШУУ^у Lublin, June 1999 Josef REHÄK Fa Speleo Zelezny Brod CZECH REPUBLIC CHARTING OF CRYOKARST FORMS ON WERENSKIOLD GLACIER (SW SPITSBERGEN) KARTOWANIE FORM KRASOWYCH NA LODOWCU WERENSKIOLDA (SW SPITSBERGEN) Abstract In the 1998 summer charting of cryokarst forms (depressions and glacier well holes) was carried out on Werenskiold Glacier based on a 1:10,000 scale map (pictures in 1990). Localization of these forms was made by a direct measurement (GPS Garmin 12 receiver), photo interpretation of the above mentioned pictures and analysis of the photographic records was made in 1998. The paper is a continuation of the previous programs (Kolondra, Pulina 1998). One of the tasks of the summer expedition (prof. Marian Pulina, June-September 1998) by the Silesian University expedition to Spitsbergen was a continuation of the works on cryokarst form chartering. Josef Rehak (with his son Marcel) as the sponsor of the next private Expedition to Spitsbergen made a great contribution to the field and a cartographic works. This time the object of studies was Werenskiold Glacier. The participants of the expedition, using the previously prepared 1:10,000 scale cartographic maps, made a list of the perceived forms measuring them in the accepted co-ordinate system (reference system ED 1950, flat co-ordinate system UTM-meridian 15°E, zone 33-X) and making their photographic records. With the help of other participants (team of prof. Jacek Jania), the measurement of glacier front reach and of several other characteristics points on its forefield was made by means of the optical telemeter. Werenskiold Glacier does not possess so many forms as Hans Glacier previously analyzed but its hydrographic system (indicating a few wells) is better recognized. The radar examinations (IGF, Polish Academy of Science and Arctic Centre University of Lapland, Rovaniemi, Finland) of the several longitudinal and transverse profiles made in the 1998 spring will allow to answer some questions concerning the glacier. 236 M. Pulina, L. Kolondra, J. Rehäk BRIEF PHYSIOGRAPHIC OUTLINE Werenskiold Glacier is situated in the SW part of Wedel Jarlsberg Land on the western coast of SW Spitsbergen. According to the Classification by V. S. Koryakin (1974) it is a valley glacier whose front ends on the land. Its surface area with the lateral glaciers is about 27 km 2 (comparison of Hornsund Fjord glacier, J. Jania [1998] glacier No 4). In the south it is bordered with the bevels of Angel (591 m), Eim (640 m) and Skal (670 m) peaks but in the north with the south bevels of Jens Erik (576 m) and Wernerknatten (635 m). To the north of the latter one, stretches the lateral Skillrygg Glacier and to the east of it another lateral Slyngfjell Glacier separated from the former by the Glasjologknausen zone (695 m). Both these glaciers, flowing down its bevels, form a characteristic central moraine which carries on its edge some material as far as the main glacier forefield. From the east it is separated from Hans Glacier by the iceshed pass Kosiba (510 m) as well as bands of the nunataks Deilegga (612 m), Staszelkammen (580 m) behind the pass Bersgskardet (463 m) and the crest Slyng (790 and 665 m). The main glacier tongue stretches about 6 km long, its average width is about 2 km. The glacier front originates from the forefield on the ordinates of 40-50 m. a.s.l. high reaching maximum heights in the upper parts of lateral glacier (about 550-580 m. a.s.l.). The average drop of the main tongue is about 5 but it is different in lateral glaciers (a little less than 4° for both north ones and almost 6° for the only one lateral glacier on the southern side Angellisen, squeezed between the bevels of the Angel and Eim peaks). Only in a small part (contact of the lateral Skillrygg Glacier with the main tongue around the bevel Wernerknatten) the drop is 11° where the most interesting surface forms of this glacier are observed. The glacier flows down WNW. Besides Hans Glacier, it is the best known on in the archipelago as far as its interior with the systems of canals, wells, chambers and draining streams is concerned. It surely has the most extensive large and medium scale cartographic records ever prepared by the Polish scientists. 1957-1959 1:500 topographic map, Werenskioldbreen Glacier. Front zone, 2 sheets (C. Lipert and his team, Military Topographic Service, Warsaw 1961). 1978 1:5,000 marginal zone relief map, 2 sheets (Jabłoński, Mechliński Szczecin 1979). 1982 1:5,000 scale marginal zone relief map (J. Jania, L. Kolondra, small poligraphy, Silesia University 1984). 1983 1:5,000 scale front part relief map (J. Jania, L. Kolondra, small poligraphy, Silesia University 1984). 1984 1:75,000 scale subject matter map, Hornsund-Geomorphology, Silesia University, Katowice 1984. 1985 1:5000 scale glacier relief map (C. Lipert, not published). 1987 1:25,000 scale topography map (Werenskioldbreen map) IGF, Polish Ac. Science, IGiK, Z. Topography, WP. Charting of cryokarst forms on werenskiold glacier (SW Spitsbergen) 237 1990 1:25,000 scale subject Matter Geological Map of the SW part of Wedel Jarlsberg Land, Spitsbergen (A. Manecki, J. Czerny, A. Kieres, M. Manecki, J. Rajchel), AGH Cracow 1993. 1994 1:25,000 scale topographic map (Hans Glacier sheet) US NPI Oslo, Universite de Quebec (only upper parts). 1999 1:10,000 scale topography map (L. Kolondra, draft autogrametric original sketch). 1:25,000 scale topographical preparation of 1:25,000 scale Glacier with its wide surrouding is planned in 1999 using the 1990 air pictures. APPLIED METHODS PREPARATION WORKS A map of the glacier location and height was prepared in 1:10,000 scale before the expedition could make a proper a list of surface cryokarst forms. Then the air pictures made in August 1990 (one stereogram: S90 4071-4072) were used. Due to the approximate solution of photogrametric structure, this elaboration was of a working character. There was used a contour line cut 5 m (for the glacier, forefield and moraine areas) and 10 m for the nearest surrounding (bevels) to the height of 100 m and the others 50 m. Besides the relief, there were chartered: glacier rivers, visible wells whose identification was evident, more important cracks (characteristic arrangement and direction), without outflow synclines as well as distinct borders of wet snow on the glacier service. The participants had blackwhite prints of air pictures and fragments of their enlargement in a 1:10,000 scale. The area of the whole glacier was thoroughly penetrated. Localized details (largely glacier wells) were measured using the GPS technique (navigational type receiver Garmin 12). The error of this type of receiver positioning is one order lower than the cartographic base accuracy (made of not too current material) but the works were of quantitative character listing. Using this technology about 850 points were measured determining their flat coordinates. At the same time for each point a verbal description was made which was later to prepare a base (Excel) and a numerical version of the glacier state in 1998 map (Auto CAD). Using the electrooptical telemeter LEICA TI6OO+DIOR 3002, the Glacier front reach (20 July 1998) and several other characteristic points were measured from the photogrametric localities (100, 101, 113, 114, 115 and 116). These points were also used for the examination of accuracy of measurements made by means of the receiver GARMIN 12. The glacier front measurement was repeated on 5 September 1998 (receiver GPS). Both ranges are included in the enclosed map. Possible changes of the situations during the last eight years have been examined. The surface of Werenskiold Glacier is characterized by much smaller surface forms (syncline type than Hans Glacier), their depths are much smaller. There are only a few large (meso) forms. A few colourful pictures registering the discovered forms were taken from the Eimfjellet bevels. Some of them were taken, bearing in 238 M. Pulina, L. Kolondra, J. Rehäk mind the future stereophotogrametric works (from the base and at suitable directions). Contemporary technological and equipment achievement^ create such possibilities. BRIEF CHARACTERISTICS OF CRYOKARST FORMS According to the classification of the cryokarst forms (Eraso, Pulina 1994; Pulina 1997) in the ablation zone of Werenskiold Glacier, some mesoforms and microform areas were distinguished which are presented in the enclosed map (original scale of the map 1:10,000) both in the form of surface signs and point symbols. In the map there were distinguished some localized forms with the designation proposed in the legend. Thus the map includes: hypsometry, front reach (1990, 1998), localization of supraglacial canals, crevices, vauclusian springs, holes of glacial wells (active and inactive), large ice fields in the glacier forefield. In the upper part of the glacier at the foot of two lateral glaciers (under Skilryggbreen at the height of 340 m a.s.l. and Slingfjellbreen at the height of 400 m a.s.l.) as well as in the upper part of central glacier part (below the rapids on which the remains of the Polish station from the half of 1950s are found) at 340 m a.s.l., large cryokarst depressions were observed. Their diameter is 150— 400 m and depth 4-8 m. They are drained by large glacier wells. One of them situated at the SW bevel of Glasjologerknaunsen (on the eastern side of the central moraine) has been explored up to a depth of 100 m (Glaciologeraven Cave) and its bottom reached the glacial circus rocky bevel. The snow was deposited in these depressions very long so they were clearly visible from the surrounding ridges of Werenskiold Glacier even at the beginning of August. In August 1998 the depressons were drained by large steams of the flow rate even several hundred 1/s. In the middle of July the cryokarst depression under Glacjologerknausen was filled with water which flowed down rapidly only at the beginning of August. Two zones of marginal cryokarst forms are found on Werenskiold Glacier. They are localized at the foot of the northern (right) bevel of Wernerknalten and Liperttoppen as well as under the southern bevel at the foot of Eimfjellet. One of these depressions situated at 330-340 m stretches along a distance of about 250 m from the mouth zone of Skilrygg Glacier to the front of Kvisl Glacier. This is an evident marginal zone connected with a large Kvisl Cave accompanied by both deeply incised meander canals on the glacier surface with the wells carrying waters into the cave and depressions in the cryokarst crater forms (most frequently with the well hole) assuming the shape of glacial uwala and hollows over the large chambers of the cave. The most frequent cryokarst mesoforms are small surface basins which are a main element of glacier drainage system in its abalation part. They are clearly visible lateral glaciers and on the glacier front in the marginal zone where the glacier slope is larger. However it is hard to make them out in the central slightly slope glacier surface due to their large area and difficulties with finding their borders. Characteristic basins are formed as shallow, long synclines reaching a depth of Charting of cryokarst forms on werenskiold glacier (SW Spitsbergen) 239 a few meters. Their interior is filled with a system of canals ending with the central one from which water flows into the glacial wells. It frequently occurs that the reopening of the well in summer causes that the stream gets to a lower situated basin. Thus deformation of a canal system of the lower situated basin takes place. Well localization in the lateral glaciers results from cracks and discontinuity zones of the glacier mass due to the contact of fronts of the lateral and central glaciers. Here a wide shallow depression is formed lengthened due to the contact of two glaciers. Numerous wells resulting from the basins situated higher are localized in it. Shallow basins situated in the glacier's upper part, just below the balance line (in 1998 this line was higher and on Werenskiold Glacier it was 420-430 m a.s.l. under Bergskardet). Resulted in the 1998 autumn from water outflow of the winter snow layer bottom (if will remain for another year). Some of these waters froze just at the snow cover foot, forming an evident hundred meter wide layer of superimposed ice of travertine and lake types (this ice is different by orginating from „snow pulp" freezing). However, some unfrozen waters are captured by the surface gullies of the basins and led to the glacier wells. The zone of this ice is clearly visible from the glacier valley levels both in the upper central part of Werenskiold Glacier and in the upper latteral part of Skilrygg, Sling and Angell Glaciers. In the front zone of Werenskiold Glacier central part there are two large basins carrying away surface waters from deeply incised meander surface canals (sometimes a few floors at a depth of several meters) to the deep well system. These are the basins of Lipertaven well and Wrocław well. These wells were explored several times. Their water is carried away to the outflows situated at the glacier foot. These springs are active in the summer period. Of the numerous wells recorded in the 1998 summer (132 wells), most are active stream swallow holes draining the surface basins. However, there are numerous inactive wells resulting from the basin draining in previous years. Around one of them, among sediments organic fossiled remains were found by the co-author (J. Rehak). Both large cryokarst depressions and small basins are drained through the central system of the insite and under glacier canals. However, marginal and local depressions are connected with a system of canals running at the point of glacier contact with the lateral moraines and rocky level of the glacier valley. The waters from these canals are carried away to large outflows at the glacier front. The flows became well known in Werenskiold Glacier both through exploration of glacier caves which are a main element of the inside glacier drainage system and through using some markers (fluoroscent and mechanical ones). The glacier water outflow places make a river system on the glacier forefield change every year. In the 1998 summer there existed three zones of outflows. The largest of them at the foot of central part glacier front (three vaucluses of which one was active at the beginning of winter season) gave the origin of the Black River. Smaller vaucluses were found in the southern part of the central glacier (Wroclaw vaucluses) feeding the stream flowing to Mewa Lake and partly the Angel Stream. These outflows were active at the beginning of the winter season. A large 240 M. Pulina, L. Kolondra, J. Rehk outflow zone was localized at the lateral front of Kvisla Glacier. The waters outflowed from a large opening of Kvisla Cave (both marginal and central zone waters also active at the beginning of the water season). Moreover, a large outflow from the local basin Lipertaven took place at the front of the same glacier in the contact point with the central moraine. It was active only in the summer season. Glacier water outflows at the beginning of the winter season froze on the glacier forefield forming vast fields of icing (naledi). When summer comes the fields melted. In 1998 the fields of icing (naledi) constituted large areas in the first half of July. A characteristic element of glacier ablation parts are ephemeral (seasonal) ice areas covered with cryokarts microforms. They are „translocated" upwards in the glacier with the disappearance of winter snow and when glacier ice is disclosed. The other areas are transformed into smooth glacial ice. CONCLUSIONS 1. Numerous cryokarst forms resulting from the central underground drainage of the glacier and marginal circulation system in the glacier were found. Localization of large central depressions is largely dependent on the place of contact of lateral and central glaciers, however, small shallow surface basins cover most glacier ablation areas. The above mentioned are connected with the hydrographic system organization on the glacier surface. The basins are drained by the underground through wells - swallow holes and the system of inside and under glacier canals. Some of these canals in the cave form were recognized during a few speleological expedition. 2. Large forms are in a similar situation for many years but smaller ones last a few years and microform surfaces are seasonal. 3. Poorly developed marginal forms were found compared e.g. with Hans Glacier. The largest northern zone of these forms is in the stage of great reductions (disappearance). 4. The analysis of a stereoscopic model on the diapositives of air pictures in the 1:50,000 scale (magnification 6x on analogous photogrametric equipment) allows to distinguish large forms because snow is deposited in them. Smaller surface basins are poorly readable but can be distinguished if the canal system around them is well developed but their bordering lines are hard to determine (small depth). Large areas of surface microforms can also be distinguished. Differentiation between the crack and supraglacial canal can be difficult because they are not accompanied by other details (e.g. wells) allowing more reliable identification. 5. Small changes have been found in the situation of cryokarst forms during the last eight years (1990-1998) but great changes have been observed on the glacier forefield. 6. Using GPS technology (portable receiver Garmin 12, navigational type) for localization of morphological details and phenomena occurring on large areas of glaciers has been successful. Localization of a phenomenon or a detail with an ac- Charting of cryokarst forms on werenskiold glacier (SW Spitsbergen) 241 curacy of several meters (or even better) on the 1:10,000 scale map was confirmed by the analysis of a few permanent elements of the map prepared from air pictures taken in 1990. REFERENCES ERASO A., PULINA M. 1994: Cuevas en hielo У rios bajo los glaciares. McGraw-Hill, Madrid, pp. 242. Instytut Geofizyki PAN 1987: Werenskioldbreen 1:25,000. Mapa topograficzna. JANIA J. 1988: Dynamiczne procesy glacjalne na południowym Spitsbergenie. UŚ Katowice, pp. 258. JANIA J. 1992: Glacjologia. PWN, pp. 359. JANIA J., KOLONDRA L., SCHROEDER J. 1994: Hans Glacier topographic map 1:25,000 Spitsbergen, Svalbard. US Katowice. KOLONDRA L„ PULINA M. 1998: Charting of surface relief forms of polar glacier on the example of the Hans Glacier. Wyprawy Geograficzne na Spitsbergen, IV Zjazd Geomorfologów Polskich, II, UMCS Lublin: 59-70. KORYAKIN S. 1974: Izmienenie razmerov lednikov Spicbergena (Svalbarda). [In:] Mater, issledovanij v oblasti oledenienija Spicbergena (Svalbarda). AN SSSRT, Moskva: 28^14. KORYAKIN S. 1975: IColebanija lednikov. [In:] Oledenenoie Spicbergena (Svalbarda). Nauka, Moskva: 80-89. Norsk Polarinstitutt 1953: Topographic Map 1:100,000, sheet B12 Torellbreen, PULINA M. 1984: Glacierkarst phenomena in Spitsberge, Norsk Geogr. Tidsskr. Oslo 38: 163-168. PULINA M. 1997: Relief of surface on subpolar glaciers. 2 4 t h Polar Symposium, Warszawa: 215-222. PULINA M„ REHAK J. 1991; Glacial caves in Spitsbergen. 1st International Symposium Glacier Caves and Karst in Polar Regions, Madrid: 87-117. STRESZCZENIE Latem 1998 roku przeprowadzono kartowanie form krasowych (depresje i otwory studni lodowcowych) na Lodowcu Werenskiolda w oparciu o mapę 1:10 000 (ze zdjęć z 1990 roku). Lokalizacje tych form przeprowadzono przez bezpośredni pomiar w terenie (odbiornik GPS Garmin 12), fotointerpretację zdjęć lotniczych oraz analizę dokumentacji fotograficznej wykonanej w 1998 roku. Praca stanowi kontynuację programu lat poprzednich (Kolondra, Pulina 1998). * This paper was written as a part of a scientific programme No P13-1021-P04/96/10 financed by the Committee of Scientific Research 1.